Telephones have long been an extension of the hand of business people who cannot live fifteen minutes without calls all over the world. So why not make a phone that doesn't take up hands or pockets? You fasten it to your palm and walk!
Or another problem: where is your phone now? Well, that is, there is no need to urgently look for him - the idea is clear. Wherever he is, and if he rings, you will have to look for him. A phone attached to the palm is relieved of such problems. Unless you leave your whole hand somewhere.
Of course, in terms of capabilities, such a phone will be inferior to its brothers, but it weighs little, takes up even less space, and the speaker and microphone are completely attached to the thumb and little finger, respectively. This is exactly the distance from mouth to ear for an ordinary person.
Putting on such a device is no more difficult than a wrist watch or a bracelet of some kind. It is also quite simple to get used to it, since it does not particularly burden the hand. In general, if in our world they did not pay such a huge tribute to traditions, the phone would certainly be in demand - it has quite a lot of advantages. But it seems to me that the developers' non-standard thinking will not find a response from potential buyers for whom image is no less important than comfort and convenience.